- add lockfile support to a2dpd

diff -u -r1.4 a2dpd.c
@@ -45,6 +45,7 @@
 #define MAXCLIENTSPERDEVICE    8
 #define MAXCLIENTSRINGSIZE     64
 #define POOLENTRYSIZE          A2DPD_BLOCK_SIZE
+#define PIDFILE                "/var/run/a2dp.pid"
 
 #define A2DPD_CONFIG_FILE       ".a2dpdrc"
 

@@ -86,7 +87,7 @@
                         case -1:
                                 exit(-1);
                         case 0:
-                                break;
+				break;
                         default:
                                 exit(0);
                 }

@@ -117,6 +118,17 @@
         printf("a2dpd [%s %s] starting ...", __DATE__, __TIME__);
 }
 
+static int lock_fd(int fd)
+{
+	struct flock lock;
+	lock.l_type = F_WRLCK;
+	lock.l_whence = SEEK_SET;
+	lock.l_start = 0;
+	lock.l_len = 0;
+
+	return fcntl(fd, F_SETLK, &lock);
+}
+
 //////////////////////////////////////////
 //////////////////////////////////////////
 // AVRCP CODE BEGIN //////////////////////

@@ -131,6 +143,7 @@
         header->packet_type = PACKET_TYPE_SINGLE;
 }
 
+
 // This function handle the bluetooth connection
 int a2dp_handle_avrcp_message(int sockfd)
 {

@@ -953,6 +966,7 @@
 int main(int argc, char *argv[])
 {
         int i = 0;
+	int fd;
         struct timespec timer_resolution = { 0, 0 };
         char address[256] = "";
         char* addr = &address[0];

@@ -960,7 +974,9 @@
         //char* iphono420= "C2:00:08:F4:30:07:64";
         //char* hpheadphone= "00:0D:44:2A:17:C7";
         struct sched_param schedparam = { sched_get_priority_max(SCHED_FIFO) };
-        int res=0,  bFork=0, bVerbose=1;
+        int res=0,  bFork=0, bVerbose=1, bKill=0;
+	FILE *fp;
+	pid_t pid;
 
         // Read config values from config file
         get_config_filename(g_srcfilename, sizeof(g_srcfilename));

@@ -993,6 +1009,10 @@
                 {
                         bVerbose=1;
                 }
+		else if(!strcmp(argv[i], "-k"))
+		{
+			bKill=1;
+		}
                 else if(!strcmp(argv[i], "+n"))
                 {
                         bFork=1;

@@ -1017,6 +1037,50 @@
         // Redirect outputs
         make_daemon_process(bFork, bVerbose, g_sOutputFilename);
 
+	// Generate the lockfile
+	fd = open(PIDFILE, O_RDWR | O_CREAT | O_EXCL, S_IWUSR | S_IRUSR | S_IRGRP | S_IROTH);
+
+	if (fd == -1) {
+		if (errno != EEXIST) // If we can't write the lock, then ignore
+			goto post_lock;
+		
+		if ((fd = open(PIDFILE, O_RDWR)) < 0)
+			goto post_lock;
+		
+		fp = fdopen(fd, "rw");
+		if (fp == NULL)
+			goto post_lock;
+
+		pid = -1;
+		if ((fscanf(fp, "%d", &pid) != 1) || (pid == getpid())
+		    || (lock_fd(fileno(fp)) == 0)) {
+			unlink (PIDFILE);
+		} else {
+			if (bKill) {
+				kill (pid, 15);
+				sleep (5); // let the other daemon die
+			} else
+				goto shutdown;
+		}
+		fclose(fp);
+
+		unlink(PIDFILE);
+		fd = open(PIDFILE, O_RDWR | O_CREAT | O_EXCL,
+			  S_IWUSR | S_IRUSR | S_IRGRP | S_IROTH);
+
+		if (fd == -1)
+			goto post_lock;
+		
+	}
+	
+	lock_fd(fd);
+
+	fp = fdopen(fd, "w");
+	fprintf(fp, "%d\n", getpid());
+	fflush(fp);
+	fcntl(fd, F_SETFD, (long) 1);
+
+ post_lock:
         printf("%s addr=%s timer=%d us [%s %s]\n", argv[0], addr, (int)(timer_resolution.tv_nsec/1000), __DATE__, __TIME__);
 
         // If we can be realtime it will be better

@@ -1036,6 +1100,7 @@
         // global free
         a2dp_exit();
 
+shutdown:
         printf("A2DPD terminated succesfully\n");
 
         return 0;